This paper examines the production run time problem with random machine breakdowns under abort/ resume (AR) policy
and reworking of defective items produced. Under AR policy, production of interrupted lot will be immediately resumed when
breakdown is fixed and machine is restored. Mathematical modeling and derivation of the production- inventory cost functions
for both systems with/without breakdowns are presented. These cost functions are integrated and long-run average cost per
unit time is obtained. Theorems on convexity and on bounds of run time are proposed and proved. A recursive searching
algorithm is developed for locating optimal run time within the bounds. Numerical example with sensitivity analysis is provided
to assist in optimal operational control of such an unreliable system.